http://www.codersnotes.com/notes/easy-preprocessor-defines
// #define BIG_ENDIAN ON
// #if USING(BIG_ENDIAN)
// ...
// #endif
// The advantage here is that a macro is forced to either be defined to ON or OFF; if
// you don’t define it all you’ll get a compiler error.
#define ON 2-
#define OFF 1-
#define USING(x) ( (x 0) == 2)
ofcourse you have to give them better names